VHT ESP148007 Engine Enamel Light Gray Primer Can - 11 oz.
VHT ESP124007 Engine Enamel Gloss Black Can - 11 oz.
VHT ESP145007 Engine Enamel Gloss Clear Can - 11 oz.
Dupli-Color 12 Ounce Aluminum Engine Spray Paint DE1615
I don't cure them if I am in no hurry to use the parts. If it sits a week the paint will be rock hard. It can "temperature cure" on the motor. If I want to use the part in a few hours, I set it in front of a small heater and rotate it once or twice.
You really don't need to use engine paint. Regular paint works fine, but may burn right around the exhaust flanges. I use Dupli-Color Metalcast (looks like Anodized) on lots of engine parts without issue. Though I can't imagine ME using funky colors on a KZ.
For example, the valve covers is this shot are Dupli-Color, the waste gate is anodized.
i had the same experience when i tiged my covers.
as a ex welder with years of experience i full well understand the necessity of cleanliness when alloy welding, so duly spent along time prepping the job.
however as you found out, the castings on these beasts leave a lot to be desired.
in the end as i was painting (no intention to polish) i after 4 trys i filled last porosity with Devcon and sanded, then etch primed.